Pulp partition molding



Dec. i2, i967 K. 1,. CRABTREE PULP PARTITI ON MOLDING 2 SheetS-Shee` l Filed Jan.

R O m V m Kamik l 'rbee Dec, l2, 1967 K. L CRABTREE PULP PARTITION MOLDING 2 Sheets-Sheet a Filed Jan.

INVENTORy Kell/260115. Clce BMM/@ A'ITvORNEYS United States Patent O 3,357,624 PULP PARTITION MGLDING Kenneth L. Crabtree, Fairfield, Maine, assignor to Keyes Fibre Company, Waterville, Maine, a corporation of Maine Filed Jan. 3, 1966, Ser. No. 518,115 2 Claims. (Cl. 229-25) ABSTRACT F THE DISCLOSURE A unitary container integrally molded of fibrous pulp material comprising a plurality of downwardly dished and relatively deep article-receiving pockets grouped around upwardly tapering hollow post formations which extend above a horizontal plane near the top of the pockets, the individual pockets being defined in part by side walls which dare upwardly and outwardly around vertical centerlines, the side walls separating two adjacent pockets comprising a pair of upwardly converging rib walls extending to substantially the same height to provide full lateral support for articles positioned in each pocket, and openings generally radially arranged with respect to the post formations separating the upper p0rtions of the rib walls from each other to increase the flexibility of the pocket side walls.

This invention relates to exible partition structure in molded pulp trays for packaging delicate or fragile globular articles, and more particularly to yieldable partition or rib structure which provides the maximum protection of deeply downwardly dished article-receiving pockets in a tray of minimum lateral dimensions.

As background, it will be recognized :that numerous arrangements have been proposed over many years for packaging delicate or fragile globular articles such as peaches, apples, light bulbs, Christmas tree ornaments, eggs and the like. Such arrangements ordinarily take the form of a horizontal tray having a plurality of downwardly dished article-receiving pockets in which such generally globular articles are individually placed for shipment. The trays when empty may be nested in compact stacks minimizing shipping and storage space, The trays when filled may be overwrapped with a flexible and usually transparent film, covered with other protective arrangements of molded pulp, either separate or hingedly attached, chipboard, plastic or other materials, or used with the upper portion of the contents exposed. Such trays additionally frequently provide attractive individual retail merchandising packages. They are often designed so that a number of filled trays may be arranged in vertical stacks and placed in larger containers for wholesale shipment. In this case, uniform width and length dimensions are required to enable the trays to be stacked in standard size shipping cases. Such trays molded of fibrous pulp materal have proved highly satisfactory because of the low initial, shipping and handling cos-ts, light weight, nestability, textured and soft surface, moisture absorbent qualities, low toxicity, easy disposability and other advantageous features of molded pulp.

The pockets long recognized as most satisfactory for delicate, globular articles in such packaging tray arrangements are commonly referred to as deep pockets. An eX- ample of a deep pocket tray is illustrated in Friday Patent 2,351,754, and may be contrasted with shallow pockets illustrated in Leitzel Patent 3,040,923. The deep type pockets have a horizontal or lateral dimension all around the upper portions of the pocket which substantially coincides with the diameter of the packaged article at the level of maximum girth of the article- The depth of such pockets is ordinarily at least approximately half 3,357,624 Patented Dec. 12, 1967 ICE the upper lateral dimension. In trays designed for globular articles which are substantially spherical, such as peaches, for instance, the pocket may be of substantially hemispherical form in downwardly dished fashion. In trays designed for globular articles which are somewhat elongated in one direction, such as eggs, for instance, the pocket in vertical-mid-cross-section is more deeply dished relative to its upper width, such as illustrated in Reifers Patent 3,199,758. In any case, it will be appreciated that such deep pockets, where the depth is at least approximately half the lateral or diametral opening at the upper portion of the pocket and the pocket encompasses essentially the entire lower portion of the article, provide full support in every lateral direction to prevent adjacently packaged articles from shifting laterally and damaging each other by direct mutual impact or contact at their levels of maximum girth. In addition, deep pocket side walls generally flare upwardly and outwardly in uniform or symmetrical fashion with respect to the vertical centerline of the pocket. Whether the side walls in plan view are substantially circular or roughly polygonal, such as generally octagonal, the walls are normally essentially equidistant-ly spaced from the vertical centerline of the pocket at any given height or level. This insures that the delicate, globular article will have its lateral contact with the side walls distributed around the pocket, and no single portion of the pocket side wall will inherently make signilicantly more lateral contact with the article than any other portion. In this way, the pocket does not have more damaging influence on the article in one place than in another.

Certain problems, however, have beenv encountered prior to the present invention with packaging trays molded of fibrous pulp material for packaging delicate, globular articles. It is obviously preferred that such deep pocket trays be designed to accommodate and protect a maximum number of articles in a tray having minimum overall dimensions. Accordingly, the packing industry has long sought a tray with all the benefits of deep pockets but with the minimum horizontal surface area characteristic of trays which permit the packaged articles to abut each other for maximum article capacity in a4 minimum unit of space.

To illustrate the problem as well as the solution provided by this invention, reference will be made herein to a tray for packaging globular, delicate fruit such as peaches, although it is to be understood that the principles of this invention have wide applicability to any molded pulp tray of the deep pocket variety. As mentioned above, it has been customary to package a predetermined number of peaches in a given size tray having predetermined length and width dimensions corresponding to long established sizes of packaging cases. In recent years, however, improved growing processes have produced peaches of larger and larger sizes, a phenomena encountered in the apple, egg and other industries as well. The increased sizes of the articles to be packaged in deep pocket trays of a given size has required, however, that the design but not the overall size of the tray be modified in an attempt properly to accommodate and protect the desired number of articles.

One suggested design modification takes the form of lowering or scooping down the height of the partition or rib structure between adjacent pockets. This permits the articles to laterally overhang the lowered rib structure so that large articles in adjacent pockets may be positioned as closely as possible to each other without, in theory, actually contacting each other. This suggestion, however, h-as proved relatively unsatisfactory in practice because significant reduction of the rib height between adjacent pockets removes the beneficial lateral support which is a recognized benefit of deep pockets. With such reduction in lateral support, the pockets really function only as shallow and not as deep pockets, and do not provide sufficient lateral support to prevent articles from shifting l-aterally and contacting each other where they overhang the lowered ribs at their points of maximum girth. Such contact promotes serious damage to the articles as they bump each other during packaging and shipment, thus this design modification does not represent `an acceptable solution to the tray design problem.

An alternate modification with which the designers of molded pulp trays have experimented involves maintaining the full desired rib height between adjacent pockets. This, however, necessitates a departure from the pocket walls which are essentially equi-distantly spaced around the pockets vertical centerline at any given height. The top of the double-walled rib takes more space than is desired between articles in adjacent pockets, and the goal of true deep pocket protection is defeated because the spacing of the rib from the centerline is frequently considera-bly less than the desired spacing of the remaining pocket walls, which are designed to coincide with the girth of the article. In other words, viewed in plan, the rib wall which separates adjacent pockets cuts a chord across the overall preferred shape of the pocket. The rib walls between adjacent pockets thus cause considerably more contact with the pack-aged article than the other portions of the pocket side wall which are adequately spaced from the pocket centerline. The top or crest of such ribs, moreover, in vertical transverse cross-section, takes the form of an inverted U shape, which involves a horizontally disposed and/ or thickened ridge of molded pulp along the upper portion of the rib. The thickened ridge of pulp forms a strong, solid barrier of molded pulp extending horizontally between adjacent articles generally at their point of maximum girth. Such 'barrier or ridge is substantially unyielding because of its solid, horizontal nature, and as already noted it is assured of more article contact because it is nearer the pocket centerline than the remainder of the pocket walls, land thus the rib itself causes as much if not more damage to the articles positioned on each side of it as the articles cause to each other with the first mentioned ineffectual ribs of reduced height.

Accordingly, it is an object of the present invention to provide partition structure between adjacent pockets to obtain the full benefits of deep pocket protection but with the articles more closely grouped in a minimum lateral area than has heretofore 'been possible.

It is another object of the present invention to provide improved rib or partition structure in deep pocket trays molded of fibrous pulp material wherein the rib or partition wall between adjacent pockets is flexible or yieldable to provide superior cushioning effects at the points of minimum lateral dimension of the pockets where pocket wall contact with the article positioned in the pocket is greatest.

Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts, and in which:

FIG. l is a top plan view of a cont-ainer according to this invention;

FIG. 2 is a cross-sectional elevational view on line 2--2 of FIG. 1;

FIG. 3 is a cross-sectional elevational view on line 3-3 of FIG. 1;

FIG. 4 is a cross-sectional elevational view of a female mold for manufacturing the container shown in FIG. 1;

FIG. S is a cross-sectional elevational view of a suggested male mold for manufacturing a container according to this invention.

Referring in more particularity to the drawings, the molded pulp container may be formed as -a unitary structure integrally molded of fibrous wood and/ or paper pulp material according to known pulp slurry deposition processes to provide a molded tray of generally uniform thickness throughout. The configuration of the preferred embodiment of this invention comprises a peach packaging tray which includes la contoured sheet having downwardly dished and relatively deep article-receiving pockets 12 for holding rounded, globular articles such as peaches. As shown in FIG. l, the tray 10 is divided into three sections 14, 14 and 14, each section being attached to but readily separable from 'an adjacent section by a perforated tear line 16, as explained more fully below. In the preferred embodiment, the downwardly dished article-receiving pockets 12 are grouped around a series of upwardly tapering hollow post formations 18.

The individual article-receiving pockets 12 each include a somewhat flattened bottom portion 20 having a centrally located aperture 22 therein. 'Ille pockets 12 further include upwardly and outwardly flaring side walls 24 curvingly connected at their lower portions to the bottom portions 20. The upper portions of the outwardly flaring side walls 24 of adjacent pockets 12 extend to substantially the same height all around the pockets, and portions of the side walls form pairs of upwardly converging rib walls 26 which function to separate two adjacent pockets in the sections 14 of the tray. The converging rib walls 26 of two adjacent pockets 12 are separated from each other by an opening 28 -at the upper portions of the rib walls to increase the flexibility of the pocket side walls, as explained more fully below. The opening 28 in the disclosed embodiment takes the form in plan view of a straight slot positioned perpendicularly across an imaginary line which connects the centerlines of two adjacent pockets. As shown in FIG. 1, the width of each opening or slot 28 is substantially constant along its length, and the slots are generally -radially arranged with respect to the hollow post formations 18. The upper extremities of the rib walls adjacent the slots are devoid of horizontal ledge or flange formations.

The container or tray 10 also comprises a series of upwardly extending embossments 30 positioned on the perforated tear line 16 which separates the adjacent tray sections 14. Each embossment 30 includes an undulated upper portion 32 having an open center 34. The embossments 30 function as reinforcing elements for strengthening the molded pulp container 10 along the lines 16. The undulated upper portion 32 of the embossment 30 provides each tear line 16 with a series of vertical sections which prevent adjacent tray sections 14 from undue flexing relative to each other about the line 16. The tray 10 also includes a plurality of apertures 36 spaced along the line 16 to allow a single tray section 14 to be more easily removed from the remainder of the tray. As stated above, the embossments 30 strengthen and reinforce the tray while the apertures 36 and open centers 34 interrupt the tear lines 16 to enable a single tray section to be readily removed from the balance of the tray.

The side walls 24 of the individual article-receiving pockets 12 flare upwardly and outwardly around vertical centerlines C passing through the apertures 22 in the bottom portions 20 of the pockets. The `walls are essentially equi-distantly spaced from the centerline at any given height or level, with the exception of the rib walls between adjacent pockets. The upwardly converging rib walls 26 form a pocket wall having an interior radial or lateral dimension 38, measured on Ya line connecting the centerlines of adjacent pockets, from a pocket centerline to an adjacent rib wall in a horizontal plane near the top of the pocket. The interior lateral dimension 38 is significantly smaller than other lateral or radial dimensions measured on a different line in the same plane from the pocket centerline to the pocket side walls. This insures firm contact of the rib `walls by the rounded articles within the pockets, even though such articles may not always make full and complete peripheral contact with the rest of the upper portion of the pocket.

The improved functioning of the structure of this invention can be illustrated by reference to certain portions of the tray shown in the drawings. For example, the tray includes relatively flexible exterior side wall portions 40 which are capable of yielding outwardly slightly if an article in the pocket 12 should have a lateral bulge which would contact these side wall portions. Such outward flexing is not hindered by a horizontal ledge or ange at the top of the side wall. 'I'he cut-out portions 36 similarly decrease the horizontal reinforcing portions and thereby tend to increase the flexibility of the adjacent side Wall portions, such as at 48, in an area Where the width o f the pocket is normal. On the other hand, side wall portions such as 42 are substantially rigid and unyielding since these portions are strengthened or otherwise reinforced at their tops by dat horizontal ledge or flange portions such as 44. In these areas, however, the pocket width is adequate to encompass the globular articles, and the unyielding wall protects rather than damages the article.

As stated above, the preferred embodiment of this invention includes pairs of upwardly converging rib walls 26 having openings 28 therein which separate the upper portions of the rib walls from each other to increase the flexibility of the pocket side Walls. The openings 28 are devoid of horizontally extending ledges or lianges, and exhibit desirable cushioning characteristics in the very area where article contact is abnormally great. The rib portions deiine the shortest lateral dimension of each article-receiving pocket from the pocket centerline. Even though the side wall portions 42 and 48 are capable of exing for the `reasons stated above, these portions along with most of the pocket side wall are equally spaced from the pocket centerline, and accordingly would not be contacted by the rounded or globular articles in the same manner or to the same extent as the articles act upon the rib walls which are disposed closer to the pocket centerline. Thus, by providing each pocket 12 with full height rib walls which are closer to the pocket centerline than the remainder of the pocket side walls to accommodate maximum numbers of large articles in a xed, standard size tray, each pocket of the tray 10 is capable of flexing in a highly satisfactory manner to thereby cushion rounded articles -adjacent the short lateral dimension and of properly supporting the rounded articles adjacent the full normal lateral dimension.

The exible partition structure of this invention also enables the deep pocket tray 10 to accommodate a maximum number of rounded or globular articles in a minimum horizontal surface area since the article-receiving pockets are closely and compactly arranged with respect to one another. Without such a structure it is clear that each individual pocket would require additional surface area in order to properly protect the articles therein which in turn would decrease the number of pockets per standard size tray. Thus, by utilizing the improved rib wall construction 26, the tray 10 is capable of supporting a maximum number of rounded articles in a highly satisfactory manner.

FIGS. 4 and 5 illustrate two open face suction forming dies for molding fibrous pulp material into the configuration shown in FIGS. 1 and 2. The female mold 50 shown in FIG. 4 includes a plurality of passageways 52 for directing suction to the exterior of the mold. A foraminous screen 54 is secured to the exterior of the mold, and blocking members or plugs 56 are fastened to the screen at selected locations to prevent the fibrous material from forming at these locations to thus provide molded apertures. A second series of plug or blocking members 58 are suitably positioned to form the openings 28 in the upper portions of the rib walls 26 of the tray.

In operation, the mold 50 is immersed in a slurry of 70 fibrous pulp material. Suction is then directed to the eX- terior of the mold through the passageways 52 to thereby 5 draw the fibrous pulp against the foraminous screen 54. Since portions of the screen are covered by the plugs 56, 58, a build-up of material is accordingly prevented at these portions. After a layer or sheet of material having the desired thickness is formed on the screen, the mold 50 is removed from the slurry, and the tray 10 is separated from the mold and dried, all in the well known manner.

The male mold 60 shown in FIG. 5 may also be utilized to form the tray of this invention. This mold includes passageways 52', a screen S4' and plugs 56', 58', all of which function in the same well known manner as the corresponding elements of the female mold 50. With such a mold, the end of the slot 28 associated with the post 18 would be vertically rather than horizontally disposed, as can be understood, to elfect article-die separation.

It is also possible to produce the slotted rib structure of this invention by cutting or slitting mechanisms, preferably associated with known after-pressing techniques, as will be apparent to those skilled inthe pulp molding arts.

While the above described embodiment constitutes the preferred mode of practicing this invention, other embodiments and equivalents may be resorted to within the scope of the actual invention, which is claimed as follows.

What is claimed is:

1. A unitary container integrally molded of fibrous pulp material comprising a plurality of downwardly dished and relatively deep article-receiving pockets grouped around upwardly tapering hollow post formations which extend above a substantially horizontal plane near the top of the pockets, the individual pockets being defined in part by side walls which Iflare upwardly and outwardly around vertical centerlines, the side walls separating two adjacent pockets comprising a pair of upwardly converging rib walls extending to substantially the same height to provide full lateral support for articles positioned in each pocket, the internal lateral dimension from a given pocket centerline to its rib wall measured in the substantially horizontal plane near the top of the pocket on a line connecting the centerline of the given pocket with the centerline of an adjacent pocket being significantly smaller than such a dimension measured on a different line from the centerline of the given pocket in the same plane, and

openings generally radially arranged with respect to the post formations to separate the upper portions of the rib walls from each other to increase the flexibility of the pocket side walls in the zone of the smaller lateral dimension, each opening taking the form in plan view of a straight slot positioned perpendicularly across the line connecting the centerline of the given pocket with the centerline of an adjacent pocket, the width of the slot in plan View being substantially constant along its length and at least as great as the normal thickness of the molded pulp material which comprises the container.

2. A unitary molded pulp container as in claim 1 wherein the openings separating the rib walls extend into the upwardly tapering hollow post formations to increase the zone of pocket side wall flexibility.

References Cited UNITED STATES PATENTS 3,163,312 12/ 1964 Chaplin 229-25 X 3,215,327 11/ 1965 Crabtree 229-25 3,2245 69 12/ 1965 Leitzel 229-25 3,243,096 3/ 1966 Crabtree 229-25 FOREIGN PATENTS 1,127,792 4/ 1962 Germany.

583,385 10/ 1958 Italy.

DAVIS T. MOORHEAD, Primary Examiner. 

1. A UNITRAY CONTAINER INTEGRALLY MOLDED OF FIBROUS PULP MATERIAL COMPRISING A PLURALITY OF DOWNWARDLY DISHED AND RELATIVELY DEEP ARTICLE-RECEIVING POCKETS GROUPED AROUND UPWARDLY TAPERING HOLLOW POST FORMATIONS WHICH EXTEND ABOVE A SUBSTANTIALLY HORIZONTAL PLANE NEAR THE TOP OF THE POCKETS, THE INDIVIDUAL POCKETS BEING DEFINED IN PART BY SIDE WALLS WHICH FLARE UPWARDLY AND OUTWARDLY AROUND VERTICAL CENTERLINES, THE SIDE WALLS SEPARATING TWO ADJACENT POCKETS COMPRISING A PAIR OF UPWARDLY CONVERGING RIB WALLS EXTENDING TO SUBSTANTIALLY THE SAME HEIGHT TO PROVIDE FULL LATERAL SUPPORT FOR ARTICLES POSITIONED IN EACH POCKET, THE INTERNAL LATERAL DIMENSION FROM A GIVEN POCKET CONTERLINE TO ITS RIB WALL MEASURED IN THE SUBSTANTIALLY HORIZONTAL PLANE NEAR THE TOP OF THE POCKET ON A LINE CONNECTING THE CENTERLINE OF THE GIVEN POCKET WITH THE CENTERLINE OF AN ADJACENT POCKET BEING SIGNIFICANTLY SMALLER THAN SUCH A DIMENSION MEASURED ON A DIFFERENT LINE FROM THE CENTERLINE OF THE GIVEN POCKET IN THE SAME PLANE, AND OPENINGS GENERALLY RADIALLY ARRANGED WITH RESPECT TO THE POST FORMATIONS TO SEPARATE THE UPPER PORTIONS OF THE RIB 